How to use printf in NHS3100 project?

I read "LPCXpresso_IDE_User_Guide.pdf" which talks about printf as below:---------------------------Semihosting C Project• Creates a simple “Hello World” project, with the main() routine containing a printf() call, which will cause the text to be displayed within the Console View of the LPCXpresso IDE. This is implemented using “semihosting” functionality. For more details, please see the FAQ athttp://www.lpcware.com/content/faq/lpcxpresso/using-printf---------------------------

Have a look at the doxygen generated documentation about this: docs/FirmwareDevelopmentDocumentation/index.html, then from the left pane Modules > Modules (weird, I know) > uarttx: Uart Tx-only module.